[Nearby] Handle profile shutdown

After the Shutdown() method is called on a BCKS, the profile must not be
used anymore. This CL cleans up current usages of the |profile_| during
shutdown and adds DCHECKs where we're sure it it still valid.

Bug: 1125056
Change-Id: I847bf7e6a96abefcc370bb5761f438ed3369c4a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2400459Reviewed-by: James Vecore <vecore@google.com>
Commit-Queue: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805658}

chrome/browser/nearby_sharing/fake_nearby_connections_manager.cc

@@ -124,7 +124,6 @@ void FakeNearbyConnectionsManager::Cancel(int64_t payload_id) {
 }
 
 void FakeNearbyConnectionsManager::ClearIncomingPayloads() {
-  DCHECK(!is_shutdown());
   base::ScopedAllowBlockingForTesting allow_blocking;
 
   incoming_payloads_.clear();

chrome/browser/nearby_sharing/nearby_sharing_service_impl.h

@@ -68,6 +68,7 @@ class NearbySharingServiceImpl
   ~NearbySharingServiceImpl() override;
 
   // NearbySharingService:
+  void Shutdown() override;
   StatusCodes RegisterSendSurface(
       TransferUpdateCallback* transfer_callback,
       ShareTargetDiscoveredCallback* discovery_callback,

chrome/browser/nearby_sharing/nearby_sharing_service_impl_unittest.cc

@@ -369,6 +369,9 @@ class NearbySharingServiceImplTest : public testing::Test {
   }
 
   void TearDown() override {
+    if (service_)
+      service_->Shutdown();
+
     if (profile_) {
       DownloadCoreServiceFactory::GetForBrowserContext(profile_)
           ->SetDownloadManagerDelegateForTesting(nullptr);
@@ -925,6 +928,7 @@ TEST_F(NearbySharingServiceImplTest, AddsNearbyProcessObserver) {
 }
 
 TEST_F(NearbySharingServiceImplTest, RemovesNearbyProcessObserver) {
+  service_->Shutdown();
   service_.reset();
   EXPECT_FALSE(mock_nearby_process_manager().observers_.might_have_observers());
 }